README.txt

AprilTags library
Detect April tags (2D bar codes) in images; reports unique ID of each
detection, and optionally its position and orientation relative to a
calibrated camera.
See examples/apriltags_demo.cpp for a simple example that detects
April tags (see tags/pdf/tag36h11.pdf) in laptop or webcam images and
marks any tags in the live image.
Ubuntu dependencies:
sudo apt-get install subversion cmake libopencv-dev libeigen3-dev libv4l-dev
Mac dependencies:
sudo port install pkgconfig opencv eigen3
Uses the pods build system in connection with cmake, see:
http://sourceforge.net/p/pods/
Michael Kaess
October 2012
----------------------------
AprilTags were developed by Professor Edwin Olson of the University of
Michigan. His Java implementation is available on this web site:
http://april.eecs.umich.edu.
Olson's Java code was ported to C++ and integrated into the Tekkotsu
framework by Jeffrey Boyland and David Touretzky.
See this Tekkotsu wiki article for additional links and references:
http://wiki.tekkotsu.org/index.php/AprilTags
----------------------------
This C++ code was further modified by
Michael Kaess (kaess@mit.edu) and Hordur Johannson (hordurj@mit.edu)
and the code has been released under the LGPL 2.1 license.
- converted to standalone library
- added stable homography recovery using OpenCV
- robust tag code table that does not require a terminating 0
(omission results in false positives by illegal codes being accepted)
- changed example tags to agree with Ed Olson's Java version and added
all his other tag families
- added principal point as parameter as in original code - essential
for homography
- added some debugging code (visualization using OpenCV to show
intermediate detection steps)
- added fast approximation of arctan2 from Ed's original Java code
- using interpolation instead of homography in Quad: requires less
homography computations and provides a small improvement in correct
detections
todo:
- significant speedup could be achieved by performing image operations
using OpenCV (Gaussian filter, but also operations in
TagDetector.cc)
- replacing arctan2 by precomputed lookup table
- converting matrix operations to Eigen (mostly for simplifying code,
maybe some speedup)